McKinney Falls State Park is located in Austin, so I can say with virtual certainty that hatched sea turtles will never be released there.
If you're referring to Matagorda Island State Park, or Padre Island National Seashore, then you're a little more likely to get somewhere in your research.
I found information on the
2001 release dates at Padre Island National Seashore, but no current information. There is a phone number (hopefully accurate), 361-949-7163, that you can call for more information.
Bingo -- did some more searching (gotta love
google.com!) and found
official National Park Service information for 2002.
Hope this helps!